We just got some board back from thermal shock and we found that several of the 2512 resistors opened up. Actaully the solder joint cracked away from the board. All other coponents look great. Boards were good before test. 10 layer board, immersion silver pads with SAC305 solder. Always the same designator too.

Now with lead free in the automotive world we include 1206 chips for the same reason. A ceramic 2512 only lasts a few hundred cycles of -40/+125C with lead free solder. A plastic bodied 2512 can go several thousand.